Manufacture of electron-discharge devices



Mar cfi 1953 w. c. BROWN MANUFACTURE OF ELECTRON DISCHARGE DEVICES Filed May 27, 1947 Patented Mar. 24, 1953 MANUFACTURE OF ELECTRON-DISCHARGE DEVICES William C. Brown, Lincoln, Mass, assignor to Rayth'eo'n Manufacturing Company, Newton, Masa, a corporation of Delaware Application May .27, 1947, Serial No. 750,851

'3 Claims. 1

This invention relates to the manufacture of electron-discharge devices, and more particularly to the assembly and manufacture of tunable electron-discharge devices of the so-called multicavit'y magnetron type.

A multicavity magnetron of the type to which this invention relates includes at least one electrode, for example, the anode thereof, in the form of a cylindrical structure, made of highly c'onductive material, such as copper, and provided with a plurality of interiorly-extending, radiallydisposed anode members, each pair of adjacent anode members, together with that portion of said anode structure lying therebetween, defining a cavity resonator. In the copending application of Erich Nevin 'Kather, Ser. No. 668,847, filed May 10, 1946, now Patent 'No. 2,529,950, granted November 14, 1950, there is disclosed and claimed a structure for mechanically tuning such a multicavity magnetron over a rather wide frequency range. Generally, this structure consists of a plurality of conducting elements, each of which is positioned intermediate a pair of adjacent anode members but spaced therefrom, so that each such element .is positioned in a separate one of the cavity resonators; these elements are movable with respect to the adjacent anode members to alter the capacitance between said members, and thereby also the resonant frequency of the magnetron. The conducting elements are integrally joined to a movable common support, so that they are all movable as a unit.

By moving a conducting element intermediate each pair of adjacent anode members, preferably, in the high-capacitance regions thereof, at the inner ends of said members, adiacent the cathode of the device, considerable additional capacitance may be added in parallel with that already existing. In order to obtain a high additional capacitance, so as to achieve as wide a tuning range as possible, it is necessary to have very small clearances between the tuning conducting elements and the anode members or vanes, while at the same time not permitting any contact between said elements and the vanes or paddles.

final assembly between these two sub'asse'mbli'es impossible. I

Therefore, an object of this invention is to devise "a method for enabling the desired small clearances between the tuning elements and the vanes 'Of a tunable 'lmfltlCal/lty magnetron 130 be 2 accurately achieved, resulting in magnetrons of wider tuning range, while at the same time reducing the number of rejects, thus cutting down the amount of scrap.

This, and other objects of the present invention, which will become more apparent as the detailed description thereof progresses, are attained, briefly, in the fOllOWiIlg manner.

While not absolutely necessary, it ha been found advisable, in order to suppress spurious oscillatio'n's in devices of the type to which the present invention relates, to provide the anode structure thereof with at least one pair of conducting straps alternately contacting successive anode members.

As above described, the anode of such a device includes a cylindrical structure or envelope provided with a plurality of anode members or vanes.

The magnetron tuner subassemb-ly, which includes a plurality of conducting elements integrally joined to a common support, as described above, each such element being intended to be positioned between a pair of adjacent anode vanes, is used as a jig for the straps and vanes of the anode subassembly. The exact optimum small separation between the tuning elements and the vanes is assured through the use of removable shims which hold or maintain the said elements and the vanes in the correct relative positions while the vanes and the tuner subassembly are both being soldered or brazed to the outer metallic envelope of the magnetron. Thus, the anode vanes are correctly located and uniformly and properly spaced, with respect to the tuning elements, for proper operation with those particular tuning elements.

Furthermore, the shims or spacing members are made of a non-solderable material, such as stainless steel, for example, and, since they are placed on each side of the tuning elements, between such element and the anode vanes, function to prevent accidental soldering of the elements to the anode vanes, which soldering would cause the device to be rejected.

In the accompanying specification there shall be described, and in the annexed drawing shown, an illustrative embodiment of the method of the present invention. t is, however, to be clearly understood that the present invention is not to be limited to the details herein shown and described for purposes of illustration only, inasmuch as changes therein may be made without the exercise of invention, and within the true spirit and scope of the claims hereto appended. For example, tunin'g devices having various shapes oi tuning fingers, different from that shown, may be utilized in the invention.

In said drawing:

Fig. 1 is a longitudinal sectional view taken through the center of a tunable multicavity magnetron, illustrating one step in the manufacture thereof, according to the present invention;

Fig. 2 is a partial bottom view of Fig. 1; and

Fig. 3 is an enlarged partial cut-away perspective view of the magnetron of Fig. 1.

Referring now more in detail to the aforesaid illustrative embodiment of the present invention, with particular reference to the drawing illustrating the same, the numeral I generally designates an electron-discharge device of the socalled tunable multicavity magnetron type, said device including an anode structure 2 and tuning means 3.

In the device shown, the anode structure includes a hollow cylindrical body or envelope 4, made of highly conductive material, such as copper, having assembled therein a plurality of radially-disposed, interiorly-extending copper anode members in the form of vanes 5, these vanes being assembled in such a position as to have their outer end faces suitably fastened, as by silver soldering or brazing, to the inner cylindrical wall of envelope 4.

In the manufacture or assembly of the device, a tuning subassembly 6 is made up. Said subassembly 6 comprises a pole piece I, an end plate 8, a plunger 9, and a diaphragm Ii]. The tubular pole piece I is hermetically sealed, as by soldering, for example, into the shallow cup-like end plate 8, said end plate having a diameter equal to the outer diameter of envelope 4. Plunger is slidably mounted in a bore I I formed in the pole piece I, the inner end of said plunger being recessed, as at I2, to accommodate the upper end of a cathode structure (not shown) in the completed device, and the lower end of said plunger being formed into a cup-shaped portion I3 which is integral with the previously-mentioned tuning member generally designated by the reference numeral 3.

The tuning member 3, which may be substantially cylindrical, comprises a plurality of integral spaced elements or fingers I4 which are adapted to straddle the anode members 5 and thereby extend into the cavity resonators formed in the anode structure 2. Each finger I4 is more or less rectangular or plate-like in shape, and is adapted to be moved intermediate a pair of adjacent anode members 5, preferably, in the high-capacitance region near the inner ends thereof.

A flexible annular diaphragm It) is secured, at its outer edge, to a portion of the lower surface of end plate 8 and, at its inner edge, to the plunger 9.

In order to provide for an external physical connection to plunger 9 for moving the same vertically, a threaded stud I5 is formed on the upper end of plunger 9 and integral therewith. Any suitable control mechanism (not shown), for example, the mechanism disclosed in the aforesaid Kather application, may be coupled to stud l5 in order to move plunger 9 and fingers I4 vertically to thereby vary the tuning of the completed device. The fingers I4 are all integral with plunger 9, so that they are all movable as a unit by movement of said plunger.

The end plate 8 is adapted to be hermetically sealed, as by soldering at I6, for example, to

envelope 4, to close the upper end thereof, the

diaphragm I0 helping to complete this closure when the device is assembled.

According to this invention, in assembling or manufacturing the device, the tuning subassembly 6, consisting of elements 'I-I0 and I3-I5 as above described, is built and assembled as a unit. The tuning subassembly is then used as a jig, in order to locate and properly space the anode members or vanes with respect to the fingers or tuning elements I4, and to maintain the anode members in positiion while they are being soldered or brazed to envelope 4 and while end plate 8 is being soldered or brazed to said envelope.

The tuning subassembly 6 is placed in position on envelope 4, with end plate 8 thereof contacting the upper end of said envelope, and said subassembly 6 is then firmly held in such position while further assembling takes place. The separate anode members or vanes 5 are then assembled in position with respect to fingers I4 of the tuning subassembly, in such a way that there is a vane on each side of each of the integrally-connected but spaced fingers I4. Thus. the anode members 5 are properly located with respect to said fingers. In order to achieve and insure the exact optimum (very small) desired separation between the vanes 5 and the fingers I4, a removable spacing member or shim I! is placed on each side of each of the elements I4, or in other words is inserted between each element and the adjacent anode member 5, so that there is a pair of such shims between each of said elements I4 and the pair of corresponding anode members 5 between which it intervenes. The shims I! are quite thin, being on the order of five mils in thickness, for example, and are made of a non-solderable material, such as stainless steel, to prevent accidental soldering of the fingers I4 to the vanes 5, which soldering cannot be tolerated since the fingers must be able to move freely with respect to the vanes for tuning purposes.

The shims II have a width at their inner ends which is somewhat greater than the radial length of fingers I4, and a length such that, when they are pushed upwardly to the upper ends of fingers I4, or to the upper ends of the slots defining such fingers, the lower ends thereof will extend a substantial distance below the bottom of envelope 4, so that, when they are in the angular position shown in Fig. 1, extending at an acute angle to the longitudinal axis of plunger 9 (the reason for this angular position will be explained hereinafter), the inner ends of each shim will cover substantially all of the side face of the corresponding finger I4, as shown in Fig. 1. Thus, non-soldering of the fingers l4 to the vanes 5, and also exact separation between the said fingers and the said vanes, are assured.

By using the tuning subassembly as a jig for the vanes, each set of vanes is matched to the set of tuning fingers with which it will cooperate during the life of the magnetron, thus eliminating the adverse effect of the cumulative tolerances which would come into play if the anode subassembly were assembled and soldered together independently of the tuner subassembly.

In order to eliminate spurious oscillations, each anode member 5 may be provided, in its lower edge, with a slot I8, the opposite side edges of the slots in adjacent anode members being provided with shoulders I9 upon which there may be seated concentrically-disposed, circular conducting straps 20 and 2|, said straps alternately contacting successive anode members and thereby assuring that alternate anode members will always be at the same instantaneous potential.

It should now be apparent that the shims i? must extend at an acute angle to the longitudinal axis of plunger 9, in order to pass outside of the straps and 2| in the downward extension of said shims below the lower end of envelope l.

The device is assembled in the manner described above, with the tuning subassembly 6 serving as a jig for the assembly of the vanes 5, and with the shims I! insuring the proper separation between the fingers It and said vanes. Since the tuning subassembly is used as a jig for vanes 5, it is also, in eifect, a jig for straps 20 and El, because these straps are in turn located by the vanes. The jig 6, due to the close frictional fit between the shims, vanes, and fingers, helps to maintain the anode members 5 in position while the soldering operation is performed. The vanes 5 are forced radially outwardly and held firmly against the inner cylindrical wall of envelope l by any suitable means (not shown), after which heat is applied to the entire assembly, as indicated by the arrows 22, in order to silver solder or braze the vanes 5 to the envelope at 23, and to similarly fasten end plate 8 to the envelope at E6, as well as to fasten straps 20 and 2! securely in position by soldering. Preferably, the assembly is inverted from the position shown in Fig. 1 While the soldering is being done, in order to maintain straps 20 and 2! in position by gravity.

After the assembly I has cooled, the shims I? may be removed and the device subjected to additional processes to complete the magnetron. Since the shims I! hold the fingers I4 and vanes 5 in position during the soldering operation, exact separation between the fingers and the vanes is assured, and, since this separation is very small, magnetrons of wide tuning range are produced, while at the same time reducing the number of rejects.

Other objects and advantages of the present invention will readily occur to those skilled in the art to which the same relates.

What is claimed is:

1. In the art of manufacturing a tunable multicavity magnetron having a plurality of separate anode members to be fastened to a common support to which is also to be fastened a tuning assembly, said assembly including a plurality of integral elements each of which is adapted to be positioned intermediate a pair of adjacent anode members, the steps of utilizing said assembly as a jig to locate and maintain said anode members in position with nonsolderable spacers, and thereafter soldering said anode members and said as sembly to said support whereby said anode members are maintained a constant predetermined distance from said tuning means during tuning.

2. In the art of manufacturing a tunable multicavity magnetron having a plurality of separate anode members to be soldered to a common support to which is also to be soldered a tuning assembly, said assembly including a plurality of integral elements each of which is adapted to be positioned intermediate a pair of adjacent anode members, the steps of utilizing said assembly as a jig to locate and maintain said anode members in position with stainless steel spacers, and thereafter soldering said anode members and said assembly to said support while said anode members are so maintained in position.

3. In the art of manufacturing a tunable multicavity magnetron having a plurality of separate anode members to be soldered to a common support to which is also to be soldered a tuning assembly, said assembly including a plurality of integral elements each of which is adapted to be positioned intermediate a pair of adjacent anode members but spaced therefrom, the steps of utilizing said assembly as a jig to locate and maintain said anode members in position, inserting a non-solderable spacing member on each side of each of said elements to properly space said anode members from said elements and to prevent soldering of said anode members to said elements. and thereafter soldering said anode members and said assembly to said support while said anode members are so maintained in position.

WILLIAM C. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,024,585 Laico Dec. 17, 1935 2,202,403 Sandberg May 28, 1940 2,257,643 Paschke Sept. 30, 1941 2,407,742 Harries Sept. 17, 1946 2,408,903 Biggs et al Oct. 8, 1946 2,422,465 Bondley June 17, 1947 

